Blueprint



Patented Apr. 18, 1944 BLUEPRIN'IJ John Holden, Reddish, Stockport, England, as-

aignor to Keuil'el & Esser Company, Hoboken, N. J., a corporation of New Jersey No Drawing. Application May 16, 1940, Serial No. 335,554. In Great Britain June 6, 1939 12 Claims. ('01. 95-6) This invention relates to a. method for the production of photographic blue-prints by semidry development with a developing solution in which the paper is only damped by the developing solution, as distinct from water development, wherein the exposed sheet is washed to remove the sensitized coating from unexposed areas.

Details of the general method for making blue prints or ferro prussiate prints by the semi-dry" method of developing-are disclosed in my U. S. Patents 2,139,264, dated February 6, 1940; 2,158,- 422, dated May 16, 1939 (reissued as Re. 21,240, dated October 17, 1939) as well as in U. S. Patent 2,014,692, dated September 17, 1935. Basically the semi-dry method for making blue prints involves the exposure to light through a pattern of a sheetoi' paper, cloth, or other support carrying a sensitized coating of photosensitive iron salts including an iron cyanogen radical. The sheet after exposure is subjected to the action of a developing solution, as distinguished from washing.

Certain preferred blue print coating solutions as well as compositions for the developer which in addition stabilize, fix, and intensify the print are given in the afore-mentioned patents.

Prints made by this semi-dry method of development, may at times show patchy lines or have a tendency to fade on exposure to light or dampness and this invention therefore has for its object to overcome these objections and to produce prints of better qualit which will be more permanent.

equivalent bases having such photosensitive coatin'gs are treated after exposure to light under a design with a thinfilm of water or with watervapor, or steam, preferably applied on the coated side and in an amount which only wets or dampens the sheet. Thereafter the developing solution, which may include stabilizing, fixing and intensifying agents, is applied to render insoluble or chemically non-reactive the term-cyanide or fern-cyanide or both and/or the iron salts, either in a ferric or ferrous state or both.

Instead of using water, water-vapor or steam alone, the water may contain wetting or penetrating agents, e. g., organic alkyl sulphonic acid salts, sulphuric acid esters of the higher fatty alcohols or the like. In addition there ma be added water-soluble agents which have a plasticizing eflect on paper. e. g'., glycerine, diethylene glycol, butylene glycol, propylene glycol to m crease the resistance of the surface to cracking and lessen the tendency of the paper to become brittle.

The pre-damping operation can be easily carried out by hand with a sponge, cloth or-cotton wool, or by a machine such as one having a roller moistening the sheet with the predamping liquid may be employed.

' According to this invention in the production of blue-prints by-semi-dry development with a developing solution, the blue print paper, after exposure to light under an image, is first predamped by the application of water, or aqueous as a film, spray, or vapor, in an amount and manner analogous to the operation of "semidry development. Subsequent to the predamping the exposed paper is subjected to the action of the developing solution. Both of these treatments, predamping and developing, simply wet the paper and donot remove the component of the blue-print coating. a

Blue print papers capable of "semi-dry" development and to which this invention relates, are those which are sensitized by a coating of an iron cyanogen compound, that is, a ferro-cyanide or a fem-cyanide or both together with a ferric salt, desirably a double iron salt, which preferably includes an alkali salt of an organic acid,

bufler salts, alkalis, acids or other suitable additions.

ACOOl'dlllg t this invention Danni's m' nthnr The second operation, referred to as the developing operation, may be carried out immediately after the predamping operation while the exposed sheet ismoist, or after a time lag, and heat may be applied between the two operations or after.

Where the predamping liquid contained a wetting agent, it may be desired to form insoluble compounds of the wetting agent to destroy its penetrating eil'ect so that correcting fluids and inks may be more conveniently applied to the print. One of the components of the developing agent such as a metallic salt may serve this purpose or an additional ingredient may be added to the developing agent to insolubilize the wetting agent. In order further to improve the print for taking correcting fluids and inks, colloids may be used in the'developing, fixing and intensifying solution.

A wetting agent may be used in the developing solution whether or not such agent formed part of the predamping solution.

The exposure to light of a sensitized blue print paper results at least in certain photochemical reactions. The ultimate development of blueprint contrast depends on subsequent reactions mhinh mi-"AA ...1...; ...l

print is directly subjected to the aqueous developing solution the essential blue print reactions and the various reactions of the compo-' nents of the developing solution with the components of the blue print coating occur simultaneously and possibly at the expense of the essential blue print reactions. Where the procedure of predamping the exposed sheet is followed as taught herein an aqueous medium is provided for some of the essential blue print reactions independently of those which stabilize, intensity or fix the print. The inclusion of a wetting agent in the predamping liquid insures that the aqueous medium will penetrate through all parts of the blue print coating.

If the wetting agent is non-volatile," or when volatile and the developing process immediately follows the predamping process, then the wetting agent may assist dispersion of the developing solution through the reactive salts.

To illustrate methods of working according to this invention some specific examples are given as follows:

Example I ,:A suitable paper is coated with an aqueous solution of the following composition:

. assasva design and a film of aqueous liquid applied to the exposed surface by passing the paper over a roller rotating partially submerged in a bath of a solution of the following composition:

Alkyl naphthalene sodium sulphonate gm 1 Water ccs 100 The print is then eitherimmediately, or after a period, passed over a roller rotating in a developing, fixing and intensifying solution of a composition described in Example I.

The pre-damping solution may contain a plasticising agent as for example:

Sodium salt of alkyl naphthalene suiphonic acid gm 1 Glycerine cc 5 Water cc 100 The glycerine may be replaced with other suitof the following composition:

Cc. Isopropyl alcohol 5 Cyclohexanol 5 Water 100 In the following example an acid is used: Phosphoric acid (conc.)' -4 cc 5 Alkyl naphthalene sodium sulphonate.. gm 1 Water cc 100 A Gms. Ferric ammonium oxilate solution 400 Sodium borate Diluted to a total volume 1,200 ccs.-

Gms. Potassiumferrocyanide solution 140 Potassium oxalate 125 Potassiumvferricyanide 30. Potassium chlorate i 250 Sugar 400 Gum arabic solution 20 Diluted to.-a totalyolume 3,200 ccs.

The solutions A and B are mixed and100 gms.

of sodium nitrite added to form the coating solution which is applied to the paper. The paper is then dried. a

After exposure to light under a design a paper so prepared is first passed over a roller rotating in a bath of water and is thereby predamped which supplies the aqueous medium for certain reactions. Then the damped paper is passed over a roller rotating in a bath of developing, fixing and intensifying solution of the following composition:

. Gms. Mono sodium ortho phosphate Magnesium sulphate 75' Potassium bromate 15 Zinc sulphate- 50 Citric acid- 10 Dissolved in 500 ccs. wate Stable prints in white lines on a brilliant blue background result.

In place of the water the pre-damping may be effected by an aqueous solution containing a wetting agent such as an ester of a sulfonated di carboxylic acid, a water soluble plasticizer'or a mixture of both.

Example. I!

tral or slightly acid is exposed to light under .a

This acid appears to have the property of preventing "bloom" which may occur when certain types of particularly hardpapers are used. and assists in the even absorption of the developer. Volatile and non-volatile wetting and penetrating agents may be used together as for example a mixture of the following composition:

Alkvl naphthalene sodium sulphonate gm 1 Cyclohexanol gm 0.5 Water s c...

promote the essential blue print reactions, which application simply was remove the components of the blue print coating and subsequently subjecting the exposed and pre-damped surface of the paper to a developing solution containing the soluble salt-of a metal which reacts to form insoluble compounds with the iron cyanogen radicals of the blue print coating and a compound for insolubilizing the iron ion, applied also in the form of the paper and does not .a film which simply wets the paper and does not remove'the components of the blue print coating and which process does not include any defined in the following v step for removingthe components of the blue print coating.

2. The method for making blue prints by the semi-dry development process which comprises a applying'to the exposed print paper an aqueous taining the soluble salt of a metal which reacts to form insoluble compounds with the iron cyanogen radicals of the blue print coating and a compound for insolubilizing the iron ion which simply wets the paper and does not remove the components of the blue print coating and which process does not include any step for removing the components of the blue print coating.

3. The method for making blue prints by the semi-dry method of development which dispenses with all washing steps which method comprises I first supplying a reaction medium for the essential blue print reactions to an exposed print which reaction medium simply wets the paper and does not remove the components of the blue print coating, then subjecting the exposed print to a developing solution containing the soluble salt of a metal which reacts to form insoluble compounds with the iron cyanogen radicals of the blue print coating and a compound for insolubilizing the iron ion which simply wets the paper and does not remove the component of the blue print coating and which process does not include any step for removing the components of the blue print coating.

4. The method for making blue prints by the semi-dry method of development which dispenses with all washing steps which method comprises first supplying an aqueous liquid as a reaction medium for the essential blue print reactions to an exposed print which aqueous liquid simply wets the paper and does not remove the components of the blue print coating, then subjecting the exposed print to a developing solution containing the soluble salt of a metal which reacts to form insoluble compounds with the iron cyanogen radicals of. the blue print coating and a compound for insolubilizing the iron ion which simply wets the paper and does not remove the components of the blue print coating and which process does not include any step for removing the components of the blue print coating.

The method for making blue prints by the semi-dry method of development which dispenses with all washing steps which method comprises first supplying water to an exposed print in an; amount suflicient to promote the essential blue print reactions which water simply wets the paper and does not remove the components of the blue print coating, then subjecting the exposed print to a film of a developing solution containing the soluble salt of a metal which reacts to form insoluble compounds with the iron cause a photochemical reaction, supplying limited amounts of a reaction medium for the prod ucts of the photochemical reaction which reaction medium simply wets the paper and doesnot remove the components of the blue print coating, subjecting the sheet to a film of a solution of developing agents'containing the soluble salt of a metal which reacts to form insoluble com-- pounds with the iron cyanogen radicals of the blue print coating and a compound for insolubilizing the iron ion which simply wets'the paper and does not remove the components of the blue print coating, and drying the. sheet without removing any of the components of the blue print coating.

7. The method -for developing exposed blue,

print paper by the semi-dry method which dispenses with all washing steps which method comprises predamping the exposed sheetwhich preclamping simply wets the paper and does not remove the components of the blue print coating,then subjecting said sheet to a film of a developing solution containing the soluble salt of a metal which reacts to form insoluble compounds with the iron cyanogen radicals of the blueprint coating and a compound for insolubilizlng the iron ion which simply wets the paper and does not remove the components of the blue print coating and which process does not include any step for removing the components of the blue print coating.

8. The method for developing exposed blue print paper by the semi-dry method which dispenses with all washing steps which method comprises predamping the exposed sheet with water containing a. wetting agent which predamping simply wets the paper and does not re-' cyanogen radicals of the blue print coating and a compound for insolubilizing the iron ion to stabilize, fix or intensify the print which simply wets the paper and does not remove the components of the blue print coating and which process does not include any step for removing the components of the blue print coating.

6. The method for making blue print photo reproductions which comprises coatin'g a paper base with a solution containing aferric salt and an iron cyanogen radical to form a sensitized sheet, exposing the sensitized sheet to light to move the components of the blue print coating. then subjecting said sheet to a developing solution containing the-soluble salt of a metal which reacts to form insoluble compounds with the iron cyanogen radicals of the blue print coating and a phosphate for insolubilizing the iron ion which simply wets the paper and does not remove the components of the blue print coating and which process does not include any step for removing the components of the blue print coating.

9. The method for developing exposed blue print paper by the semi-dry method which dispenses with all washing steps which method comprises predamping the exposed sheet with water containing a material having a plasticizing efiect on the paper which predamping simply wets the paper and does not remove the components of the blue print coating, then subjecting said sheet not include any step for removing the components of the blue print coating.

10. The method for developing exposed blue print paper by the semi-dry method which dispenses with all washing steps which method comprises predamping the exposed sheet with water containing a volatile wetting agent which predamping simply wets the paper and does not removethe components of the blue print coating,

then subjecting said sheet to a developing solution containing the soluble salt of a metal which reacts to form insoluble compounds with the 4- see ers iron cyanogen radicals or the blue print coating print coating and which process does not include and a compound for insolubilizing the iron ion any step for removing the components of the which simply wets the paper and does not reblue print coating.

move the components 0! the blue print coating 12. The method for developing exposed blue and which process does not include any step tor I print paper by the semi-dry method which disremoving the components of the blue print coatpenses with all washing steps which method coming. prises applying limited amounts of water to the 11. The method for developing exposed blue exposed sheet which water simply wets the paper print paper by the semi-dry method which disand does not remove the components or the blue penses with all washing steps which method com- 10 print coating, then subjecting said sheet to the prises predamping the exposed sheet with water action of a. developing solution containing the containing a wetting agent which 'predamping soluble salt of a metal which reacts to form insimply wets the paper and does not remove the soluble compounds with the iron'cyanogen radcomponents 01' the blue print coating, then subiculs of the blue print coating and a compound jecting said sheet to a developing solution con- 15 for insolubilizing the iron ion to stabilize, fix or talning an agent for destroyingthe eflect oi the intensity the print which simply wets the paper wetting agent and also containing the soluble and does not remove the components of the blue salt of a metal which reacts to term insoluble print coating and which process does not include compounds with the iron cyanogen radicals of any step for removing the components of the the blue print coating and a compound for insola blue print coating. ubilizing the iron ion which simply wet: the paper JOHN HOLDEN. and does not remove the components of the blue 

